The present invention relates to remote convenience systems, and is particularly directed to a system which includes a remote transmitter for transmitting a message to cause a function, such as a vehicle location alerting function (e.g., xe2x80x9cvehicle finderxe2x80x9d function), to be performed.
Remote convenience systems are known in the art. Such remote convenience systems permit remote control of certain functions. One example type of a remote convenience system is for remotely controlling vehicle functions. Other example types of remote convenience systems include garage door opener systems and entry light activation systems.
Focusing now on the remote convenience vehicle systems, examples of a remotely controlled functions include locking and unlocking of one or more vehicle doors. A remote convenience vehicle system that permits remote locking and unlocking functions is commonly referred to as a remote keyless entry system.
Such remote convenience vehicle systems may provide for control of other vehicle functions. For example, a remote vehicle locator function may be provided. The vehicle locator function causes the vehicle horn to emit a horn chirp and/or the headlights of the vehicle to flash xe2x80x9cONxe2x80x9d. This allows a person to quickly locate their car within a crowded parking lot.
Known remote convenience vehicle systems include a receiver mounted in an associated vehicle and at least one portable hand-held transmitter located remote from the receiver. The receiver has a memory that stores one or more security codes, each of which is associated with a transmitter that is authorized to cooperate with the receiver mounted in the vehicle. Each transmitter is provided with one or more manually actuatable switches. Each switch is associated with a vehicle control function to be performed. The transmitter includes circuitry that responds to the actuation of one of its switches to transmit a message in the form of a digital signal. The transmitted digital signal also includes the appropriate security code. When the receiver receives such a digital signal, it compares the security code portion of the received signal against its stored security code, and, if a match is found, the receiver provides the received message to an actuation controller, which, in turn, directs performance the requested function.
The portable transmitters operate in the ultra high frequency (xe2x80x9cUHFxe2x80x9d) portion of the radio frequency (xe2x80x9cRFxe2x80x9d) spectrum. Specifically, the remote transmitters operate in the portion of the RF spectrum that is allocated by the Federal Communication Commission (xe2x80x9cFCCxe2x80x9d) for unlicensed transmission devices. FCC regulations stipulate that such unlicensed devices can not have a transmitted signal strength that exceeds a stipulated maximum value.
It is desirable to have a system which will provide consistent performance within a certain range. However, one problem associated with the UHF band is that of multipath interference. This problem manifests itself as xe2x80x9cdead spotsxe2x80x9d inside of what would otherwise be a distance at which the system is capable of operating. These xe2x80x9cdead spotsxe2x80x9d are caused by destructive interference and their location relative to the point of transmission are (i) frequency (i.e., wavelength) dependent and (ii) strength of signal dependent. Because the FCC regulates the transmitted signal strength, transmission power cannot merely be increased to overcome the interference and, thereby, obviate the problem of dead spots.
Further, it is often desirable to accomplish remote control performance of certain functions at a longest possible distance. One example is the remote vehicle locator function. To illustrate such a scenario, consider a shopping mall patron exiting a shopping mall building and being faced with the task of visually locating their car within a vast shopping mall parking lot. It would be beneficial to be able to actuate the remote vehicle locator function from a location near the exit door of the shopping mall, before proceeding into the parking lot.
In accordance with one aspect, the present invention provides a receiver/controller apparatus for a remote convenience system. The apparatus is responsive to a function request transmitted by a portable transmitter for controlling performance of a function. Means receives at least a portion of a first signal. The first signal conveys a message that contains a function request. Means receives at least a portion of a second signal. The second signal conveys the same message that contains the function request. Means discerns at least a portion of the message from the first signal which is associated with a first frequency. Means discerns at least a portion of the message from the second signal which is associated with a second frequency. The second frequency is different from the first frequency. Means controls performance of the requested function conveyed in the message.
In accordance with another aspect, the present invention provides a method for receiving a remote convenience function request transmitted by a portable transmitter to control performance of a function. At least a portion of a first signal is received. The first signal conveys a message that contains a function request. At least a portion of a second signal is received. The second signal conveys the same message that contains the function request. At least a portion of the message is discerned from the first signal which is associated with a first frequency. At least a portion of the message is discerned from the second signal which is associated with a second frequency. The second frequency is different from the first frequency. Performance of the requested function conveyed in the message is controlled.